Method for recording a visible image on a substrate by using an electroconductive toner

ABSTRACT

This invention relates to a method for recording a visible image by forming an electrostatic charge image or an electric field image on a photoconductive insulating layer or a dielectric layer which is disposed on a substrate or a dielectric sheet or film and connecting said electrostatic charge image or said electric field image to said visible image by contacting said electrostatic charge image or said electric field image with an electroconductive toner sprinkled on said photoconductive insulating layer or said dielectric layer or said dielectric sheet or film, thereby to form said visible image, and fixing said visible image on said photographic insulating layer or said dielectric layer or said dielectric sheet or film under heating or in the presence of a solvent vapor.

Takeuchi et a1.

METHOD FOR RECORDING A VISIBLE IMAGE ON A SUBSTRATE BY USING ANELECTROCONDUCTIVE TONER Inventors: Satoshi Takeuchi, Iruma District,

Saitama Prefecture; Hachiro Saito, Narashino, Chiba Prefecture, both ofJapan Dai Nippon Insatsu Kabushiki Kaisha, Tokyo, Japan Filed: July 25,1969 Appl. No.: 845,040

Assignee:

Foreign Application Priority Data Aug. 15, 1968 Japan 43-58340 Aug. 15,1968 Japan 43-58341 References Cited UNITED STATES PATENTS 1/1962Carlson 118/637 Jan. 29, 1974 3,630,608 12/1971 Sage ass/17 3,311,4903/1967 Fauser 355/10 X 2,624,652 l/1953 Carlson 355/3 X 3,002,43410/1961 Reuter 355/3 x 3,263,649 8/1966 Heyl 118/637 PrimaryExaminer-John M. Horan Attorney, Agent, or Firm-Wenderoth, Lind andPonack 5 7] ABSTRACT This invention relates to a method for recording avisible image by forming an electrostatic charge image or an electricfield image on a photoconductive insulating layer or a dielectric layerwhich is disposed on a substrate or a dielectric sheet or film andconnecting said electrostatic charge image or said electric field imageto said visible image by contacting said electrostatic charge image orsaid electric field image with an electroconductive toner sprinkled onsaid photoconductive insulating layer or said dielectric layer or saiddielectric sheet or film, thereby to form said visible image, and fixingsaid visible image on said photographic insulating layer or saiddielectric layer or said dielectric sheet or film under heating or inthe presence of a solvent vapor.

4 Claims, No Drawings METHOD FOR RECORDING A VISIBLE IMAGE ON ASUBSTRATE BY USING AN ELECTROCONDUCTIVE TONER Also this inventionrelates to a method for recording a visible image by forming anelectrostatic charge image on a photoconductive insulating layer or adielectric layer which is disposed on a substrate or a dielectric sheetor film, and transferring said electrostatic charge image to a freshphotoconductive insulating layer or a fresh dielectric layer or a freshdielectric sheet or film, and then converting said transferredelectrostatic charge image to said visible image by contacting saidelectrostatic charge image with an electroconductive toner sprinkled onsaid fresh phoconductive insulating layer or said fresh dielectric layeror said fresh dielectric sheet or film thereby to form said visibleimage, and fixing said visible image on said fresh photoconductiveinsulating layer or said fresh dielectric layer or said fresh dielectricsheet or film under heating or in the presence of a solvent vapor.

Furthermore, this invention relates to a method for recording a visibleimage by transferring the visible image which is disposed on aphotoconductive insulating layer or'a dielectric layer which is disposedon a substrate to a fresh photoconductive insulating layer or a freshdielectric layer or a fresh dielectric sheet or film before said visibleimage is fixed to said photoconductive insulating layer or saiddielectric layer, and then fixing said transferred visible image on saidfresh photoconductive insulating layer or said fresh dielectric layer orsaid dielectric sheet or film under heating or in the presence of asolvent vapor.

This invention relates to an improvement of the electrophotography orthe electrography for recording a visible image on a photoconductiveinsulating layer disposed on a substrate or on a dielectric layerdisposed on a substrate or on a dielectric sheet or film.

In particular, this invention relates to improved methods as summarizedhereinafter.

l. A method for recording a visible image by forming an electrostaticcharge image by exposing a light pattern on a photoconductive insulatinglayer disposed on a substrate after it was sensitized by a coronadischarge, and converting said electrostatic charge image to saidvisible image by contacting said electrostatic charge image with anelectroconductive toner sprinkled on said photoconductive insulatinglayer.

2. A method for recording a visible image by forming an electrostaticcharge image on a dielectric layer disposed on a substrate or by formingan electrostatic charge image on a dielectric film or sheet by using asuitable charged electrode and converting said electrostatic chargeimage to said visible image by contacting said electrostatic chargeimage with an electroconductive toner sprinkled on said dielectric layeror said dielectric sheet or film.

3. A method for recording a visible image by forming an electrostaticcharge image on a photoconductive insulating layer or a dielectric layerwhich is disposed on a substrate or a dielectric sheet on film by theconventional procedures, transferring said electrostatic charge image toa fresh photoconductive insulating layer or a fresh dielectric layer ora fresh dielectric sheet or film by the conventional techniques such asTESI process, and converting said transferred electrostatic charge imageto a visible image by contacting said transferred electrostatic chargeimage with an electroconductive toner sprinkled on said freshphotoconductive insulating layer or said fresh dielectric layer or saidfresh dielectric sheet or film.

4. A method for recording a visible image by forming an electrostaticcharge image on a photo conductive insulating layer or dielectric layerwhich is disposed on a substrate or a dielectric sheet or film by theconventional procedures, contacting said photoconductive insulatinglayer or said dielectric layer or said dielectric sheet of film with afresh dielectric sheet or film in tightly or placing saidphotoconductive insulating layer or said dielectric layer or saiddielectric sheet or film at a place slightly apart from a freshdielectric sheet or film thereby to produce an electric field imagecorresponding to said electrostatic charge image and then supply anelectroconductive toner on said fresh dielectric sheet or film toconvert said electric field image to said visible image.

5. A method for recording a visible image by placing a dielectric sheetor film on the convex patterns disposed on a plate, forming an electricfield image corresponding to said convex patterns on said dielectricsheet or film by applying an electric voltage to said plate and thenconverting said electric field image to said visible image by supplyingan electroconductive toner on said dielectric sheet or film.

6. A method for recording a visible image by transferring the visibleimage which was formed on a photoconductive insulating layer or adielectric layer which is disposed on a substrate ora dielectric sheetor film by the procedures as mentioned above to such a member as a freshphotoconductive insulating layer or a fresh dielectric layer which isdisposed on a substrate or a fresh dielectric sheet or film bycontacting said visible image with said fresh members to which saidvisible image is to be transferred in tightly in the presence of anelectric field or by supplying a corona discharge to a back surfaceoofsaid fresh member, or by placing said visible image at the placeslightly apart from said fresh member which said visible image is to betransferred in presence of electric field or by supplying a coronadischarge to a back surface of said fresh member.

7. In the methods as mentioned above, it is noted that the visible imageis fixed under heating or in the presence of vapor of a solvent such asa water or an organic solvent.

Heretofore, there were proposed in the art various kinds of theelectrophotographic techniques which are exemplifed by xerography andelectrofax and therefore the basic principles of such techniques areknown in the art. The prior electrophotography is characterized byforming an electrostatic charge image on a photoconductive insulatinglayer disposed on substrate by using a conventional technique byexposing a light image on said photoconductive insulating layer aftersaid layer was sensitized by a corona discharge, and then by developingsaid electrostatic charge image by using a developing technique in whicha colored and triboelectrically charged electro-insulating powder isused as a toner. In carrying out such developing technique, it isconventional to use a relatively coarse granule, which is the so-calledcarrier, such as a plastic bead, an iron powder or the like in additionto the colored and triboelectrically charged electro-insulating powderas in the cascade process and a magnetic brush process. Also, afur-brush developing process is practiced by using a hair-like carrier,and a powder-cloud process is practised in which no carrier is used.

In carrying out an electrographic process, an electrostatic charge imageis formed on a dielectric sheet or film by using suitable electrodes oran electron beam and then the electrostatic charge image is developed byusing the developing technique mentioned above in which the colored andtriboelectrically charged electro-insulating toner is used.

In carrying out a xeroprinting process, an electrocharge is induced onan electro-insulating pattern disposed on an electroconductive materialby a corona discharge and then the electro-charge is developed in thesame manner as mentioned above.

It is therefore noted that the common feature of the prior knowntechniques reside in the use of a colored and triboelectrically chargedelectro-insulating toner. Such prior known techniques have a commondefect, which is referred to as an edge effect, causing the degradationof the visible image formed. The edge effect results in the visibleimage having a non-uniform density because the electric line of force isconcentrated on the outline of the electrostatic charge image and thedensity is increased on the outline of the visible image. The edgeeffect is greater enhanced if the electrostatic charge image having abroad area is developed. Therefore, when an original pattern having thebroad area is copied by the prior techniques, the resultant copy issubjected to the edge effect and suffers degradation. Also it isimpossible to produce a copy of originals having a continuous tone byusing the prior techniques due to the presence of the edge defect. Suchdefect was a fatal obstacle to the development of the priorelectrophotographic or electrographic technique.

In order to remove the above mentioned defects inherent to the priorelectrophotographic or electrographic techniques, many investigationshave been made in the field of dry and wet developing methods but theydo not yield good results.

The object of this invention is to provide new methods forsatisfactorily removing the edge effect so as to be able to copy theoriginals having a continuous tone. For achieving the object of thisinvention, it is characterized by the use of a colored andelectroconductive powder as a toner which is contrary to the colored andelectric-insulating toner used in the prior electrophotographic orelectrophotographic techniques.

In the prior electrophotographic r electrographic techniques, it is alsoproposed to use a developing electrode for removing the edge-effect andpreventing the concentration of the electric line of force on theoutline marked with the electrostatic charge image. In such a case, theedge effect is reduced when an electroconductive carrier such as a metalpowder, for example, an iron powder is used because such a carrier actsas an electrode for developing the electrostatic charge image. The edgeeffect is remarkable when an electroinsulating carrier such as a plasticbead or metal powder coated with an electro-insulating material is used.

In prior magnet brush developing process, it is sometimes observed thatfine particles of ferromagnetic powders (carrier) adhered to theelectrostatic charge image which was formed on the photoconductiveinsulating layer or dielectric layer. This is considered that becausethe ferromagnetic powders are charged with an electric charge contraryto the electric charge of electrostatic charge image by theelectrostatic induction phenomenon, the attractive force acts betweenthe electrostatic charge image and the ferromagnetic powder. It isconsidered that the attractive force between the electrostatic chargeimage and the ferromagnetic powders is generally not too powerful and'solarge size particles of ferromagnetic powders are easily removed by themagnet, but small size particles of ferromagnetic powders are retainedon the electrostatic charge image.

It is assumed that any powdered materials having goodelectro-conductivity can be adhered to the electrostatic charge image byusing the electro-charge which is induced by the electrostatic inductionphenomenon and it was found by the inventors that this is realized andalso that the electrostatic charge image can be developed by suchpowdered materials. Namely, it was found by the inventors that when suchan electroconductive powdered material (electroconductive toner) issprinkled on the electrostatic charge image under such a condition asthat if the external force can be neglected, it can be adhered to theelectrostatic charge image in an amount varied depending on the amountof the electro-charge of the electrostatic charge image.

In such a case, the'photoconductive insulating layer or the dielectricsheet or film on which the electrostatic charge image is formed can bedipped in the electroconductive toner which is stored inelectroconductive container or the electroconductive toner can beuniformly sprinkled on the electrostatic charge image in a large amountand so such an electroconductive toner itself does not adhere to theelectrostatic and consequently a good visible image from which the edgeeffect I can be completely eliminated is obtained.

As is obvious from the foregoing, the electroconductive toner is used inaccordance with this invention. Such an electroconductive toner is notelectrically charged under normal conditions and has no ability toadhere electrically to any materials under normal conditions. As is wellknown when an object is placed near an electro-charged material, theobject is charged with an electro-charge, which is contrary to theelectrocharge of the electro-charged material, at one end near theelectro-charged material and the object is simultaneously charged withan electro-charge, which is the same electro-charge as that of theelectro-charged material, at the other end of the object far from theelectro-charged material. This phenomenon occurs byelectric-conductivity when the object is made of an electroconductivematerial. Also, this phenomenon caused by polarizing action when theobject is made of a dielectric material. When an electroconductiveobject is placed near an electro-charged material and then said objectis electrically grounded to the earth, said electroconductive object ischarged with an electro-.

charge which is contrary to the electro-charge of the electro-chargedmaterial. When the electric circuit between the electroconductive objectand the earth is cut off, the electroconductive object can retain anelectrocharge which is contrary to'electro-charge of the electro-chargedmaterial. This principle is well known and it is illustrated by themechanisms of an electrophorus and an electrostatical generator.

This invention can also be illustrated by referring to the aboveprinciple. For example, an electrostatic charge image is formed on aphotoconductive insulating member such as an amorphous selenium plate ora zinc oxide-resin paper by subjecting said photoconductive insulatingmember to the corona discharge, exposing a light pattern on saidphotoconductive insulating member, sprinkling an electroconductive tonerall over said member and then sweeping an excess amount of theelectroconductive toner by inclining or vibrating said photoconductiveinsulating member or by using other procedures while theelectroconductive toner is adhered to and retained on said electrostaticcharge image. The adhesion and retension of the electroconductive toneron the electrostatic charge image is based on the fact that the toner ischarged with an electrocharge which is contrary to the electro-charge ofthe electrostatic charge image after the excess amount of said toner isremoved from the photoconductive insulating member.

The electroconductive toner used in this invention is selected fromelectroconductive water-soluble high molecular substances such aspolyvinyl alcohol, polyvinyl pyrrolidone, gelatine, polyacrylic amidesand the like, organic compounds such as urea, starch, sodium alginate,sugar and the like, and inorganic materials such as Fe, Cu, Al, sodiumchloride and cupric sulfate. Also, certain materials having lesselectric-resistance can be used as the electroconductive toner. Such anelectroconductive toner is used in the powdered state and the bulkconductivity of the particles of such a toner can be practicallyneglected because the surface electric conductivity of the particles orthe easy mobility of the electro-charge induced by the electrostaticinduction phenomenon is effectively utilized in accordance with thisinvention. Therefore, certain materials having high electric reistancecan also be used in this invention when the outer surface of theirparticles is treated to have the electro-conductivity orto reduce thesurface electric resistance of the particles.

The prior electrophotographic or electrographic developing technique isbased on the phenomenon of triboelectrification. Thus, it is commonsense that the toner must have triboelectric charge of polarity contraryto that of the electrostatic charge image which is formed on aphotoconductive insulating or dielectric layer or a dielectric sheet orfilm. For instance, for positive-to'positive development, it isnecessary to use a electronegatively charged toner in the xerographicprocess and also it is necessary to use a electropositively chargedtoner in the electrofax process. When the electropolarity of the toneris the same as that of electro static charge image, positive-to-negativedevelopment is accomplished but the obtained visible image is not ofgood quality. Thus, in the prior technique, it is necessary to controlthe triboelectric charge of toner used in order to obtain a good visibleimage; therefore it is necessary to select the material for thetoner-carrier combination higher in the triboelectric series, and alsoit is necessary to mix the charge control agents with the toner or applya specific treatment on the surface of a carrier. Also, the material forthe toner itself must have a high electric resistance in the priortechnique.

On the contrary, the electroconductive toner used in this invention isnot required to be triboelectrically charged, because the negativeelectric charge is induced in the electroconductive toner when it comesnear to or contacts with the electrostatic charge image which iselectrically positive, also the positive electric charge is induced inthe electroconductive toner when it comes near to or contacts theelectrostatic charge image which is electrically negative. Consequently,

there is produced an electrostatic attractive force between theelectrostatic charge image which is disposed on a dielectric layer or anelectrophotographic layer or a dielectric sheet or film and theelectroconductive toner which has an electrostatically induced charged,and therefore the toner adhered to the charge image. Thus, thepositive-to-positive development is always accomplished in thisinvention, no matter whether the electrostatic charge image iselectrically negative or positive, therefor the material for the tonerused in this invention can be widely varied and easily selectedindependently of their triboelectric characteristics. It is mostpreferable to use a dipping procedure for carrying out a developing stepin accordance with this invention. The dipping procedure is carried outby dipping the dielectric layer or the photoconductive insulating layerwhich is disposed on a substrate or the dielectric sheet or film, onwhich the electrostatic charge image is formed, into theelectroconductive toner and then by sweeping the excess amount of saidtoner from said substrate or said sheet or film by vibrating orinclinating said substrate or said sheet or film. Also, theelectroconductive toner can be sprinkled uniformly and continuously onthe surface of said substrate or said sheet or film on which theelectrostatic charge image is formed or contacted with the surface ofsaid substrate or said sheet or film on which the electrostatic chargeimage is formed.

As mentioned above, the electroconductive toner is electrically adheredto the electrostatic charge image and therefore care must be taken notto rub the surface of said member by applying an unnecessarily strongmechanical force in order to produce a good visible im age. Thus, it isdesired that the electroconductive toner is contacted with theelectrostatic charge image under the static condition without rubbingthe surface of the electrostatic charge image. In such a case, thedevelopment can not be carried out with high speed but such a developingprocedure is very simple. It is, however, possible to carry out thedevelopment with high speed by moving the electroconductive toner at thesame speed as that of the photoconductive insulating layer or dielectricsheet or film having the electrostatic charge image as illustrated inExamples because the electroconductive toner is in the static conditionrelative to' the photoconductive insulating layer or the dielectricsheet or film.

Now it is necessary to fix a visible image on the dielectric layer orthe photoconductive insulating layer or the dielectric sheet or film inorder to complete the improved electrophotographic or electrographictechnique of this invention. In the conventional fixing steps, theelectroconductive toner which consists of powdered metals or theircompounds can not be used because they can not be melted under the usualheating or in the presence of a solvent vapor. It is, however, possibleto use the powdered metals in this invention for fixing the visibleimage when such powdered metals are coated with a good electroconductiveand easily fusible or a water-soluble material such as an organicsubstance or a high molecular substance such as sugar, a phenol resin,an alkyd resin and a polystyrene resin. Japanese Pat. Publication No.2633/68 discloses that the saturated fatty acids can be used as thecoating materials and also Japanese Pat. Publication No. 2634/68discloses that the thermoplastic or fusible resins and the saturatedfatty acids can be used as the coating materials. It is, however, notedthat such saturated fatty acids and such resins are electro-insulativematerials which are different from the electroconductive materials usedin this invention. Also it is noted that the conventional powderedmaterials having high electric resistance can also be used'in thisinvention after they were coated with any electro-conductive materialbecause such conventional powdered materials are fusible under heatingor soluble in the presence of a solvent vapor and such powdered materialcan be leached out and fixed on the dielectric or photoconductiveinsulating layer or the dielectric sheet or film when theelectroconductive material is broken during the fixing step of thevisible image.

Thus, the visible image is fixed on the dielectric or photoconductiveinsulating layer or the dielectric sheet or film and the copy of theoriginal is made. When the visible image is transferred to the othermember by using the conventional transferring procedure, the visibleimage disposed on the dielectric or photoconductive insulating layer ordielectric sheet or film is put on the other member in layers tightlybonded and then the visible image is subjected to the corona dischargeor rolled with an electrode .such as a roller which is supplied with anexternal electric voltage.

It should be noted that the electro-insulative toner used in the priorelectrophotographic techniques can be tightly adhered to theelectrostatic charge image by the electric force in light but that inthis invention the electroconductive toner can not be tightly adhered tothe electrostatic charge image in light because the electric charge ofthe electrostatic charge image escapes and also the electric chargeinduced on the electroconductive toner vanishes in light. Therefore, thetransferring step of this invention can be carried out in the samemanner as in the conventional transferring procedures in the dark, andthe transferring step of this invention can be carried out more easilywhen it is carried out in the light.

Further, it is an interesting matter that when the toner is anelectroconductive ferromagnetic powder, the electroconductive magnetictoner adhered to the electrostatic charge image can be transferred bythe action of a magnet to the other member which is spaced apart fromthe member which has visible image composed of the electroconductiveferromagnetic toner, because the magnetic attractive force toelectroconductive ferromagnetic toner is very powerful.

It is obvious from the foregoing that this invention can be applied tothe dielectric sheet or film on which the electric field image isformed. in accordance with this invention, the visible image can beproduced on a dielectric sheet or film by putting it on a member onwhich the electrostatic charge image is formed and by supplying theelectroconductive toner on said dielectric sheet or film because theelectroconductive toner is charged with the electric charged by actionof the electric field which is produced through said dielectric sheet orfilm due to the electric charge of said electrostatic charge image whichis disposed on said member and the electroconductive toner adheres tothe area of surface of said electrostatic charge image. Then thedielectric sheet or film on which the visible image was produced isremoved from the member which has the electrostatic charge image. Insuch a case the member which has the electrostatic charge image can berepeatedly used because the visible image is not produced directly onsaid member.

This invention is illustrated by the following Examples.

EXAMPLE 1 A paper was coated with a photoconductive insulating layerhaving thickness of 2 to 4 by applying a photoconductor-resin paint tosaid paper. The photoconductor-resin paint was prepared by mixing zincoxide, silicone resin and rose bengal in the weight ratio of 50 l0 0.1.The photoconductive insulating layer had good photoconductivity but itcan be replaced by a commercial electrofax paper. The photoconductiveinsulating layer was sensitized by the negative corona discharge in thedark and then the sensitized layer was ex posed to a light image havingthe broad area of picture to form an electrostatic charge image. 200grams of an iron powder of**300"to"500"mesh"was coated with a fixingmaterial which was prepared by mixing with shel lac, methyl alochol andsorbitan monolaurate in the weight ratio of 10 50 0.01, and had amelting point of C to C. The coated iron powder was sprinkled on theelectrostatic charge image disposed on the paper and then the excessamount of the coated iron powder was swept from the paper by incliningsaid paper to develope the electrostatic charge image into a visibleimage having no edge effect. The visible image was good but it wasdamaged when it was placed in the light and rubbed. Therefore, thevisible image was fixed under heating at a temperature ,of 100 to 150Cin the dark.

EXAMPLE 2 Example 1 was repeated with the exception that thephotoconductive insulating layer used in Example 1 was replaced by analuminum plate having a thin layer of amorphous selenium which wassensitized by the positive corona discharge. Also it can be replaced bya commercial zerographic plate. The resultant visible image was good asin Example 1.

Further, it was observed that the similar results are achieved when theiron powder used in Examples 1 and 2 was replaced by at least one powderselected from the group consisting of Al, Zn, Sn, Ni, Cu, brass andtheir alloys or at least one powdered metal which was prepared byelectrically plating or electroless-plating a powder selected from thegroup consisting of Al, Zn, Sn, Ni, Cu and Cr with at least one of suchmetals.

EXAMPLE 3 Examples 1 and 2 were repeated with the exception that thecoated iron powder used in Examples 1 and 2 was replaced by a graphitepowder coated with a fixing material used in Example 1 for producing agood visible image.

Further, it was observed that the similar results are achieved by usinga powdered material selected from the group consisting of carbon black,gelatine, shellac, casein, gum arabic, starch, methyl cellulose,hydroxyethyl cellulose, polyacrylamide, polyvinyl pyrrolidone,polyvinyl, alcohol, water soluble resin, in oxide, silver chloride, ironphosphate, lead acetate, crystalline inorganic compounds, pigments anddyestuffs. Some of the materials mentioned above could not be fixed onthe electrostatic charge image under heating but it was found that theycan be fixed on the electrostatic charge image under heating after theywere treated with the fixing material as shown in Example 1.

EXAMPLE 4 A colored and electric insulating polystyrene powder wasprepared by dissolving 100 grams of polystyrene resin, which is referredto Picolastic D-l (ESSO Company), in 200 cc of methylethyl ketone,adding grams of carbon black to the solution, ball-milling the mixturefor 24 hours, evaporating methylene ketone under heating and pulverizingthe mixture into fine particles by using a jet mixer after the mixturewas cooled. The polystyrene powder thus produced was treated with anaqueous solution containing 1 to 5 grams of gelatine, 100 grams of waterand 0.0] gram of polyoxyeth ylene sorbitan monostearate for impartingelectric conductivity to the surface of the polystyrene powder. Thecoated powder was dried and was then used as a toner in the same manneras in Example 1 for obtaining a black visible image. The black visibleimage was fixed on the photoconductive insulating layer disposed on thepaper in the same manner as in Example 1 by heating it at a temperatureof 100 to 150C to fuse the polystyrene resin.

Further, it was found that any colored, pulverizable insulating resincan be used in this invention after it was powdered into fine particlesand then the particles were coated for improving their electricconductivity. Also, it was found that it is preferable to use anantistatic agent in course of the preparation of the polystyrene powderfor reducing its electric insulating resistance.

EXAMPLE 5 Example 2 was repeated with the exception that the coated ironpowder was replaced by a toner which was prepared as follows.

grams of gelatine and 2 grams of aniline blue were throughly dissolvedin 100 cc of hot water and the solution was dried and the resultantmixture was pulverized into fine particles. The surfaces of theparticles were treated with an alcohol solution containing 20 percentshellac and a small amount of titanous chloride and then the treatedparticles were dried to form the electroconductive toner.

EXAMPLE 6 A capsulated powder was prepared from a solution containing adyestuff (or a coloring material) by using the coacervation techniquedisclosed in the Fuji Shashin Film Report, No. 14, pages 77 to 84published in the year 1966. The capsulated powder was treated with thefixing material as shown in Example 1 and the treated powder was used asa toner in the same manner as in Example 1 for obtaining a good visibleimage.

EXAMPLE 7 An iron powder was treated with an electroconductive fixingmaterial which was prepared by using a mixture of 10 weight parts of acopolymer of polyvinyl acetate and crotonic acid, 50 weight parts ofwater and 0.01 weight part of an antistatic agent (alkylbenzenesulfonate), and the treated iron powder was used as a toner forconverting an electrostatic charge image into a visible image. It wasobserved that the visible image was almost not transferred to apolystyrene sheet when the visible image was spaced from the polystyrenesheet at the distance of l to 3 millimeters in the dark room and anegative or a positive corona discharge was applied to said sheetatbehind said sheet. Also, it was observed that the visible image wasalmost not transferred to the polystyrene sheet when an electrode wasplaced behind said sheet and 500 to 10,000 volts were applied to theelectrode.

It was, however, observed that the visible image was effectivelytransferred to the polystyrene sheet when the visible image was closelycontacted with said sheet and the corona discharge was applied at behindsaid sheet. The transferred visible image was fixed under heating attemperature of to C.

A further experiment was carried out by spacing the visible image fromthe polystyrene sheet at the distance of 1 to 3 millimeters in thelight. It was found that the visible image was effectively transferredto the polystyrene sheet and the visible image was fixed under heatingat a temperature of 100 to 150C.

Still further, it was observed that when a toner was made by treating aferromagnetic powder (iron powder) with the fixing material as mentionedabove and the toner was used in the same manner as mentioned above, thevisible image can be transferred to the polystyrene sheet by using notonly the electric transferring technique but also by using the magnetictransferring technique in which a magnet is used.

EXAMPLE 8 An electrostatic charge image was formed on the commercialelectrofax paper and then the electrostatic charge image was transferredto a polyester sheet by using the conventional techniques. Thetransferred electrostatic charge image was developed by using the toneras mentioned in Example 4. It was found that the transferredelectrostatic charge image can be converted into a good visible image.

EXAMPLE? A copy of an original having a continuous tone was made byusing the toner as mentioned in Example 5 and a photoconductive membermade of an inorganic photoconductor such as zinc oxide, amorphousselenium, cadmium sulfide or an organic photoconductor such aspolyvinylcarbazol. It was found that the quality of the copy varieddepending on the property of the photoconductor used and also that thecopy was affected by gamma (7) values of the photoconductive member. Forexample, the commercial electrofax paper or zerox plate gave the copyhaving high contrast but the photoconductive member made of cadmiumsulfide or polyvinylcarbazole gave the copy having low contrast. it wasfound that the best photoconductor was the powdered pure cadmium sulfidewhich was doped with copper in an amount of 10 10 molar percent. Such aphotoconductor was dispersed in an adhesive such as epoxy resin and thedispersion was used for forming a photoconductive insulating layer.

EXAMPLE 10 An electrostatic charge image was formed on a commercialelectrostatic recording paper which has a dielectric layer on a paper byusing a needle-like electrode which was applied with 200 to 1,500 voltsand then the electrostatic charge image was developed by using the toneras mentioned in Example 5. it was found that a good visible image wasformed even if the electrode was given either negative voltage orpositive voltage.

Also, it was found that a good visible image was formed when anelectrostatic charge image was formed on a commercial electrostaticrecording paper by using a plate having the convex patterns which wasapplied with 200 to 2,000 volts and then the electrostatic charge imagewas developed by using the toner as mentioned in Example 5.

EXAMPLE 1 1 An electrostatic charge image was formed on a commercialelectrofax paper and then cellophane was adhered to the electrostaticcharge image without forming the static marks and the toner as mentionedin Example 4 was sprinkled on the cellophane. It was found that avisible image was formed on the surface of the cellophane. The visibleimage was fixed under heating at a temperature of 100 to 150C, and thenthe electrofax paper was stripped out from the cellophane. The strippedelectrofax paper can be re-used.

Also, it was found that the visible image can be fixed in the cellophaneby using the above toner without damage after the visible image wasplaced in the light.

EXAMPLE 12 An electrofax paper was sensitized by the corona dischargeand then the sensitized electrofax paper was covered with a transperentpolypropylene sheet. An electrostatic charge image was formed on thesensitized electrofax paper by exposing it to a light image passingthrough the polypropylene sheet. A toner as mentioned in Example 4 wassprinkled on the polypropylene sheet to produce a visible image on thepolypropylene sheet and then the visible image was placed in the lightroom. The polypropylene sheet was stripped out from the electrofax paperand then the visible image was fixed on said polypropylene sheet byusing conventional fixing techniques.

EXAMPLE 13 A xeroprinting plate was sensitized by exposing it topositive or the negative corona discharge and an electrostatic chargeimage was formed and then it was developed with the toner in the samemanner as in Example 5. A good visible image was formed on thezeroprinting plate, and then it was transferred to a paper byconventional method. Resultant visible image was fixed on the paperunder heating at a temperature of 100 to 150C.

EXAMPLE 14 A plate having the convex patterns was used as an electrodeand the plate was contacted with a polystyrene sheet and then 200 to2,000 volts were applied to the plate. Then the toner as mentioned inExample was sprinkled on the back surface of polystyrene sheet while thevoltage was held at 200 to 2,000. It was found that a visible image wasformed in accordance with the convex pattern on the back area of thesheet which is contacted with the convex area of the plate by the actionof the electric field.

The present Example shows the fact that the visible image can berecorded by the action of the electric field and also that the toner iselectrostatically bonded to the electric field image. The visible imagewas fixed on the polystyrene sheet by the conventional techniques afterthe electric field vanished.

EXAMPLE 15 An electrofax paper was sensitized by exposing it to thenegative corona discharge in the same manner as in the conventionaltechniques and then the sensitized paper was exposed to a light image toform an electrostatic charge image on the electrofax paper. Theelectrostatic charge image formed on the electrofax paper was immersedin a powdered electroconductive magnetic toner having a size of 5 to 50p.. The magnetic toner was prepared as follows.

grams of finely powdered magnetic oxide of iron were mixed with 20 to 30grams of polystyrene resin which is referred to Piccolastic D-lOO andsold by ESSO Company and the mixture was pulverized. l0 grams of thepulverized powder was dispersed in 100 grams of a water solutioncontaining 5 grams of lauryl trimethylammonium chloride (an antistaticagent). The resultant dispersion was dried to produce theelectroconductive magnetic toner.

An excess amount of the toner retained on the electrofax paper was sweptfrom said paper by vibrating it and a good visible image was formed onthe electrofax paper. The visible image disposed on the electrofax paperwas placed in the light room and the visible image was covered with acellulose paper and then a magnet was placed near behind of thecellulose paper. It was found that the visible image is effectivelytransferred to the cellulose paper. The visible image can be fixed onthe cellulose paper under heating at a temperature of 100 to C.

EXAMPLE 16 Example 15 was repeated with the exception that a coarsepowder of iron was additionally added to the toner used in Example l5.The coarse powder of iron has a size of l00 to 500 u. The presentExample proved that the step for sweeping an excess of the tonerretained on the electrofax paper can easily carried out.

Further, it was observed that the similar results are achieved by usingglass particles which are treated with stannous chloride or glassparticles on which metallic aluminum was deposited under vacuumevaporation or glass particles on which copper was plated without theuse of electric current.

EXAMPLE 17 In carrying out of Example 15, it was observed that theexcess amount of the toner can not be completely removed from thesurface of the electrofax paper but it was found that the toner retainedon the area on which the toner must not be adhered can easily be sweptby cascading the coarse powder used in Example 16.

In this Example, the density of the visible image was slightly reducedbut it was found that there is no defect in practice.

EXAMPLE 18 An electrostatic charge image formed on an electrofax paperwas loosely contacted with the toner, which is mentioned in Example 1and sprinkled over the surface of an aluminium plate. It was found thata good visible image is formed on the electrofax paper after the paperwas removed from the aluminium plate. A slight contamination due to thetoner retained on a part of the electrofax paper not having the visibleimage can be removed by vibrating said paper or cascading the coarsepowder used in Example 16. The visible image was fixed on the electrofaxpaper at the place but the visible image can be transferred to acellulose paper in the same manner as in the conventional techniques andthen the transferred visible image can be fixed on the cellulose paper.

EXAMPLE 19 Example 18 was repeated with the exception that the aluminiumplate was replaced by a napped cloth such as velvet goods. It was foundthat a good visible image is formed on the electrofax paper.

EXAMPLE 20 A concave portion of a photogravure-like copper plate was fedwith the toner as mentioned in Example 5 and the copper plate wascontacted with an electrofax paper having an electrostatic charge image.The copper plate was made by known plate-making process to have gravurecells having a size of 100 to 200 lines per inch and the toner was fedinto the concave portion of the copper plate. When the copper plate wascontacted with the electrofax paper, the toner adheres to theelectrostatic charge image to develope it into a netlike visible image.It is noted that the gravure cells can be replaced by grained cells,mosaic cells and other desired types of cells.

EXAMPLE 21 In the present Example, a movable and rotary copper drumwhich is provided with the gravure cells having a size of 100 to 200lines per inch was used for carrying out the method of this invention athigh speed. The drum was moved and rotated at high speed in contact withan electrostatic charge image disposed on an electrofax paper while thegravure cells were continuously fed with the toner as mentioned inExample 5 by using the doctor members. It was found that a good visibleimage is formed on the electrofax paper.

Also, the present Example can be modified by using a rotary copper drumwhich is stationary. The electrofax paper having the electrostaticcharge image was passed through the space between the drum and a rubberroller.

It was found that the developing can be carried out at a speed of 50 tometers per minutes.

We claim:

1. A method for recording a visible image, characterized by:

a. sensitizing a photoconductive insulating layer disposed on a suitablesubstrate by corona discharge,

b. placing a transparent dielectric sheet onto the sensitizedphotoconductive insulating layer;

0. projecting a light image on said sensitized photoconductiveinsulating layer by passing a light through said transparent dielectricsheet, thereby producing an electrostatic charge image on saidsensitized photoconductive insulating layer, said electrostatic chargeimage causing an electric field image corresponding to saidelectrostatic charge image on said transparent dielectric sheet;

d. converting said electric field image into a visible image bycontacting said electric field image with an electroconductive tonersprinkled on said transparent di-electric sheet, and

e. fixing said visible image on said transparent dielectric sheet byheating.

2. A method for recording a visible image, according to claim 1, whereinthe step for converting the electrostatic charge image or the electricfield image to said visible image is carried out by contacting a plateor drum having concave cells in which the electroconductive toner isfed, with the surface of the fresh dielectric layer having thetransferred electrostatic charge image or the transparent dielectricsheet having the electric field image.

3. A method for recording the visible image according to claim 1,wherein the step for converting the electrostatic charge image or theelectric field image to said visible image is carried out by cascadingor flowing a mixture of the electroconductive toner andelectroconductive coarse granules over the surface of the freshdielectric layer having the transferred electrostatic charge image orthe transparent dielectric sheet having the electric field image.

4. A method for recording the visible image according to claim 1,wherein the step for fixing the visible image on the fresh dielectriclayer or the transparent dielectric sheet is carried out in the presenceof a solvent vapor.

2. A method for recording a visible image, according to claim 1, whereinthe step for converting the electrostatic charge image or the electricfield image to said visible image is carried out by contacting a plateor drum having concave cells in which the electroconductive toner isfed, with the surface of the fresh dielectric layer having thetransferred electrostatic charge image or the transparent dielectricsheet having the electric field image.
 3. A method for recording thevisible image according to claim 1, wherein the step for converting theelectrostatic charge image or the electric field image to said visibleimage is carried out by cascading or flowing a mixture of theelectroconductive toner and electroconductive coarse granules over thesurface of the fresh dielectric layer having the transferredelectrostatic charge image or the transparent dielectric sheet havingthe electric field image.
 4. A method for recording the visible imageaccording to claim 1, wherein the step for fixing the visible image onthe fresh dielectric layer or the transparent dielectric sheet iscarried out in the presence of a solvent vapor.